Sahih Bukhari Volume 8, Book 73, Hadith Number 119.

Narated By Hudhaifa : From among the people, Ibn Um ‘Abd greatly resembled Allah’s Apostles in solemn gate and good appearance of piety and in calmness and sobriety from the time he goes out of his house till he returns to it. But we do not know how he behaves with his family when he is alone with them.